Low-Cost Manufacturing of Autoclave-Grade Composite Structures Outside of an Oven

Current manufacturing of advanced composites generally utilizes convective heating and pressure applied by an autoclave oven. This curing process accounts for ~25-50% of the component acquisition cost, and can be greatly reduced using a novel ONA manufacturing approach developed in a collaboration between the Metis Design Corporation (MDC) and the Massachusetts Institute of Technology (MIT). ONA stands for Out-of-oven conductively heated Nano-porous network enhanced Accelerated cure cycle. Using ONA, autoclaves or ovens are replaced with flexible resistive CNT surface heaters, which is much more energy efficient. Nano-porous networks (NPN) are sized and dispersed appropriately to promote resin flow and consolidation through capillary pressure, and improve interlaminar toughness by locally creating a polymer nanocomposite (PNC). Accelerated curing can be achieved using the CNT heats that have low thermal mass, and the fact that there is no volume of air to heat in the ONA approach. ONA has proven to produce high-quality, void-free laminates with identical mechanical properties (and improved damage tolerance) compared with autoclave-cured laminates using existing prepreg systems. Compared to traditional autoclave curing, ONA benefits include 2-3 orders of magnitude reduction in total power consumption, 1.5-3x faster cycle-times, elimination of geometric constraints of a pressure vessel, and enabling low-cost tooling.